Because standing seam roof constructions utilize sheet metal roof panels, it is frequently necessary to install a relatively thick blanket of insulating material immediately beneath the sheet metal roof panels to minimize heat transfer through the roof. In a typical installation sequence, the blanket of insulating material is placed in position upon the purlins of the roof framework, a series of bracket-like roof panel mounting clips are mounted on top of the blanket along a purlin by self-tapping screws which pass through the blanket to secure the clips to the purlin, and one standing seam edge of a sheet metal roof panel is then placed over and secured to the panel mounting clips. A second set of panel clips is then installed adjacent the opposite standing seam edge of the roof panel, similarly secured to the underlying purlins, and the next roof panel is installed in the last mounted set of clips.
Because the roof panels involved are relatively long and narrow, a typical standard panel having a length of twenty feet and a width of two feet, the panel mounting clips on a given purlin are spaced from each other by a distance equal to the panel width--that is two feet--and each installed panel clip compresses the insulating blanket between the clip and purlin. Because the clips are spaced from each other by only a relatively short distance along the purlin, the insulating blanket, in its finally installed condition, has a region of substantially reduced thickness along and adjacent to each roof purlin. Because the effectiveness of the heat insulating blanket is dependent upon its thickness, these regions in which the blanket is compressed along each purlin offer substantially less resistance to the flow of heat through the roof. This effect may be observed on heated buildings after a light snow fall--the locations of the purlins can be readily identified by regions of melted snow while the remaining roof remains snow covered.
It has been proposed to minimize this effect by installing, on top of the insulation blanket, a board-like block of insulating material, such as styrofoam, to provide an increased thickness of insulating material over the region which is compressed along and adjacent to the purlins (See, for example, U.S. Pat. No. 4,058,949). However, the installation of such blocks is complicated by the fact that such blocks must be located in position before the overlying roof panel is installed, and the installation of the panel frequently disturbs the location of the blocks. This problem arises because the roof panel, which is installed with its long dimension normal to the longitudinal extent of the purlins, will extend across several purlins, thus necessitating laying several individual blocks of insulating material, one over each purlin, before the roof panel is moved into position. Once the panel is moved into or close to its finally installed position, the insulating blocks are concealed beneath the panel. It is usually necessary to shift the roof panel being installed longitudinally into the desired side-by-side alignment with the previously installed roof panel. It is in the placing of the roof panel that the location of the insulating blocks can be disturbed. Once the roof panel is in its final position, the panel presses the block against the top of the insulating blanket so that the block does not move, but during the placement of the roof panels, this action may displace the insulating block from its intended position.
The present invention is especially directed to a method and an apparatus for overcoming the problem discussed above by employing a simple wire clip which can be mounted upon one end of the insulating block and engaged with the panel mounting clip or bracket to prevent displacement of that end of the insulating block during the subsequent installation of a roof panel.